When water or many other fluid mixtures are cooled below freezing, the material changes from a liquid state to a solid state, and undergoes a significant expansion in volume, which is as much as 10% or more for water or water-based mixtures. When water freezes in a pipe, it undergoes a similar expansion. Water that has frozen in pipes or other confined spaces does more than simply clog the pipes and block flow. When freezing occurs in a confined space like a steel pipe, the ice will expand and exert extreme pressure which is often enough to crack the pipe and cause serious damage. This phenomenon is a common failure mode in hot-water heating systems and automotive cooling systems.
Ice forming in a pipe does not always cause cracking where ice blockage occurs. Rather, following a complete ice blockage in a pipe, continued freezing and expansion inside the pipe can cause water pressure to increase downstream. The increase in water pressure leads to pipe failure and/or cracking. Upstream from the ice blockage the water can retreat back towards its inlet source, and there is little pressure buildup to cause cracking.
Liquid cooling systems for electronic devices are occasionally subjected to sub-freezing environments during shipping, storage, or in use. Since these systems are going to be frozen on occasion, they must be designed to tolerate the expansion of water when frozen. Additives, such as antifreeze, are potentially poisonous and flammable and can damage mechanical components, sensitive sensors, and electronics, which is why pure or substantially pure water is typically the coolant of choice.
What is needed is an apparatus for and method of preventing cracking in a liquid cooling system that can tolerate a predetermined level of freezing and expansion inside confined spaces without damaging electronic components or affecting system performance.